One type of display panel described in copending application Ser. No. 051,313 of George E. Holz and James A. Ogle, filed June 22, 1979, includes a thin metal plate having a large number of small-diameter holes. At the present time, these holes are formed by means of a laser, and this hole-forming operation is generally satisfactory. However, one problem is that the material of the metal plate which is removed by the laser sometimes deposits on the surface of the plate near each hole as it is formed. This results in an uneven surface and non-uniform spacing of the plate from other associated structures in the panel. One solution which is employed comprises coating the metal plate with a protective insulating coating, but this requires extra steps. The present invention provides a solution to this problem.